Retention Starts at Recruitment: Enrolling People Who Stay

A participant who withdraws at month four costs more than one who never enrolled: procedures spent, a randomization slot consumed, and statistical power lost. Sites treat retention as a mid-study workstream, but the strongest predictors of dropout are set before day one.

Enroll for fit, not just eligibility

Meeting inclusion criteria isn't the same as being able to complete the study. At pre-screening, probe the practical fit:

• Does the visit schedule survive contact with their work and family reality?
• How far is the commute, and how will they make it?
• Do they understand the placebo arm and still want to participate?
• Are they joining for reasons the study can actually satisfy?

A gentle "this study asks a lot — walk me through how the every-two-weeks visits would fit your schedule" filters kindly now instead of expensively later.

Set expectations that survive month three

Enthusiasm-based recruiting produces month-one participants. Honest recruiting produces completers. The burdens named plainly during consent — visit length, washout discomfort, diary requirements — become manageable knowns rather than accumulating grievances.

The first two weeks decide a lot

Early experience disproportionately shapes commitment. Fast wins: a welcome call after visit one ("any surprises? questions?"), visit reminders that respect their preferred channel, on-time stipend processing, and one named contact person. Participants who feel like people rather than subjects in week one behave like partners in month six.

Feed retention data back to recruitment

Close the loop quarterly: which recruitment sources, which pre-screen answers, which expectation gaps correlate with early withdrawal? Sites that adjust their screening conversations based on why people actually drop out steadily shift their enrollment mix toward completers — which is what sponsors are really buying.